This invention relates to snap action electrical switches.
Electrical switches typically operate to open and close an electrical circuit by moving one or more contacts between contact positions. In some cases, the switch contacts may be damaged by slow movement of the contacts between switch positions or other improper actuation of the switch. For example, if a switch contact is moved slowly when opening a current-carrying circuit, arcing between contacts as the circuit is opened can cause the contacts to overheat, erode or otherwise be damaged. Some switch arrangements also allow switch contacts to be held in a transient state between on and off switch positions, i.e., teased between switch positions, and can cause contact damage.
In one aspect of the invention, an electrical switch apparatus includes a snap action element by which switch contacts can be rapidly moved between switch positions. In one aspect of the invention, the snap action element makes the switch apparatus teaseproof so that the switch contacts cannot be held in a transient position.
In one illustrative embodiment, a switch apparatus includes a handle, a snap action element and a switch contact apparatus. Rotary movement of the handle is transmitted by the snap action element to the switch contact apparatus so that movable contacts in the switch contact apparatus may be moved between contact positions, thereby opening or closing at least one electrical circuit. The handle is coupled to the snap action element so that rotation of the handle causes a first portion of the snap action element to rotate. Rotary motion of the first portion in the snap action element is transmitted via a resilient member to a second portion of the snap action element so that the second portion moves rapidly and in a teaseproof manner to a second position. The second portion may be coupled to the electrical switch contact apparatus so that the movable switch contacts are driven by the movement of the second portion.
In one aspect of the invention, a switching apparatus includes a housing having a handle end and a switch end. A handle drive arm is rotatably mounted at the handle end of the housing so that the handle drive arm has a range of rotary motion of approximately 90 degrees, and a switch drive arm is rotatably mounted at the switch end of the housing so that the switch drive arm has a range of rotary motion of approximately 45 degrees. A resilient member interconnects the handle drive arm and the switch drive arm so that rotation of the handle drive arm causes rotation of the switch drive arm. In one embodiment, a snap rotation of the switch drive arm is caused by rotation of the handle drive arm so that the switch drive arm moves rapidly between switch positions.
In another aspect of the invention, a switch apparatus includes a housing having a handle end and a switch end. A handle drive arm is rotatably mounted at the handle end of the housing, and a switch drive arm is rotatably mounted at the switch end of the housing. A spring interconnects the handle drive arm and the switch drive arm so that rotation of the handle drive arm causes a snap rotation of the switch drive arm. A plate is mounted between the spring and one of the handle drive arm and the switch drive arm, e.g., to shield the spring from either the handle drive arm or the switch drive arm during movement.
In another aspect of the invention, a switch apparatus includes a handle, an electrical contact apparatus having a movable switch contact, and a snap action element that transmits rotary motion of the handle to the electrical switch contact apparatus so that rotation of the handle causes movement of a movable switch contact in the electrical contact apparatus. The snap action element includes a first end plate, a handle arm stop plate fixed to the first end plate, and a handle drive arm rotatably mounted at a first end to the handle arm stop plate. A recess in the handle arm stop plate receives the handle drive arm. The snap action element also includes a second end plate fixed relative to the first end plate, a switch arm stop plate fixed to the second end plate, and a switch drive arm rotatably mounted at a first end to the switch arm stop plate. A recess in the switch arm stop plate receives the switch drive arm. A spring is connected at second ends of the handle drive arm and the switch drive arm opposite the first ends so that rotation of the handle drive arm causes snap rotation of the switch drive arm.
These and other aspects of the invention will be apparent from the following detailed description and the appended claims.